DNA testing is being used for genetic genealogy. We are now

Genetic genealogy gives genealogists a means to check or supplement the historical record with information from genetic data. A positive test match with another individual may:

    * provide locations for further genealogical research
    * help determine ancestral homeland
    * discover living relatives
    * validate existing research
    * confirm or deny suspected connections between families
    * prove or disprove theories regarding ancestry

For a site on genetic evolution visit the Genographic  Project
...Atlas of Human Journey

You can advance the high-light to a different era and for each there is a video below. Most interesting how they gather information.

Explore the site, it has many avenues.

For more information/education this Eupeida link offers many studies.

It too, has many avenues to explore.

Here is a great set of illustrated genetic tutorials.

On my 'Mahoney' side, I did the Family Tree yDNA test as a part of the O'Mahony Society DNA program.

The current results can be viewed at this link at
O'Mahony Society site. (My Kit# is 89269).

The latest two reports are recommended.